Questions tagged [seismic]

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Predicting rock type from seismic processing

In reflection seismology, we create a source with an airgun and then use receivers to register acoustic waves (an approximation) at the surface. From these measurements, we can predict a velocity ...
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5 votes
1 answer
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Is there a seismic discontinuity between the lithosphere and asthenosphere?

I've been learning about seismic discontinuities, mainly the 5 defined ones - Conorod discontinuity, Mohorovicic discontinuity, Repetti discontinuity, Gutenberg discontinuity, and Lehmann ...
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Seismicity associated with post glacial rebound

Allied to the question: Why is relative sea-level falling in Hudson Bay?, where the surviving answers mention post glacial rebound. Is seismicity associated with post glacial rebound and if so what is ...
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Are there specific layers in the subsurface that come before gas or oil?

Currently, I've started working on a geophysics project. More specifically, I'm trying to find gas and oil reservoirs in SEGY files using deep learning. I've been reading about seismic reflection ...
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What are the boundary conditions for Navier's Equations of motion in seismic?

Navier's equations of motion in seismic have 3 solutions, according to how it is resolved (boundary conditions): for Vp (compression waves) for Vs (shear waves) for Vr (Rayleigh waves) I know the ...
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Preconditions for stacking

Some of the requisite for stacking is that the noise and amplitudes need to be uncorrelated. Can someone explain to me why? Also is there a drawback for stacking?
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Quality control in Seismic Acquisition - shot offset shift

I have a problem with seismic data where the minimum offset of the shot is not centered at the nearest receiver, this shift can be for 3 traces 2 or one and maybe more in the two sides !! So is there ...
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1 vote
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Conversion of SEG-Y relative to MSL

I am working on the conversion of CSF file from SonarWiz into SEG-Y data. However, it comes back always related to the Sensor depth/altitude and never to the MSL. I have tried changing the bytes from ...
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1 answer
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Recent high seismic activity in Europe

It seems that Europe and the Mediterranean Sea have had high seismic activity in last six months. Major events which I remember are: 2020 Aegean Sea earthquake, magnitude of 7.0 Mww 29 December 2020:...
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1 answer
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What would be the phase shift and polarity of a seismic wave upon reflection

What would be the phase shift and polarity of a seismic wave a) when it hit the free surface b)when the free surface reflection goes down and hit a reflector and returned to the receiver placed on the ...
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Beam forming FK analysis of a seismic wave

So after reading alot of literature on source localization, I found out that FK analysis is one of the most widely used methods to determine source location without explicitly calculating the ...
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1 vote
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How does uplift lead to onlapping?

I read in a paper that: Interpretation of 2-D seismic lines shows the lower to middle Patchawarra Formation onlapping onto paleostructural highs at approximately 270 Ma and again at 273 Ma, ...
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How do we know the speed of S-waves (shear waves) in the Earth's inner core? Has this been measured?

Wikipedia's Seismic wave includes the plot below of the speed of S and P waves as a function of depth in the Earth. In the region of the outer core the speed of S-waves or shear waves is shown to be ...
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Q factor estimation from VSP

in seismic data processing there is a step of calculating the absorption represented By Q value which is Q factor , how we can estimate it from VSP ! thank you.
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2 votes
3 answers
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stretch phenomena after NMO application on seismic data

after the NMO application we have stretch for far offset , i read a lot of articles but i can't have a complete idea how this phenomena is really created ! any one have a rich explanation ?
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1 answer
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Where can I find broadband seismic reflection data?

or what type of companies should I contact to ask for the data? This data would be produced from Seismic Vibroseis survey trucks which are mostly used to locate oil and gas. I doubt most oil and gas ...
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1 answer
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Why do P waves have a higher velocity in the lower mantle than in the core even though the core has a much higher density?

I've just started teaching 9th grade Earth science and my students and I have noticed something about P and S wave depth vs velocity graphs. In the typical graph, eg: https://www.researchgate.net/...
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1 answer
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Hydrophone/geophone sensor sensitivity - noise versus signal

Today, a student asked this question, and I was unable to answer it in a way that was understandable and accurate - even for myself. For seismic data acquisition projects, how are sensors able to '...
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2 votes
1 answer
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Using an accelerometer as a geophone to conduct a seismic survey

I am doing a capstone project for a sensor systems course and I would like to write a python program to acquire, process and present seismic data like that of seismic surveys. Is it possible using ...
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1 vote
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Finding out actual dip and dip direction of refractor

We have two traveltive curves for first arrivals (direct and refracted) from a dipping refractor in the forward and reverse directions along a profile line. my question is: Is there a logical way (non-...
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1 answer
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Is it reasonable to approximate the swinging building (base of the building) during an earthquake to a simple harmonic motion?

I am thinking of making a model of swinging building during earthquake and study the methods to minimize the swinging. So does it even makes sense to approximate the swinging buildings (the base of ...
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4 votes
0 answers
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Seismic velocity inversion & analysis

I attended at talk recently at the TGS office in Houston, TX, by Marianna Raunch. During this talk, a statement was made that for "very large" velocity inversions, semblance (or other similar ...
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1 answer
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Wave train 200 m/s meaning

I ran a 60 m line intended for surficial seismic refraction. Energization with hammer. 12 (10 hz vertical 5 m spaced) geophones and 5 shots (15 m spaced). Record length 0.5 s. Thanks to a borehole ...
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4 votes
1 answer
140 views

wavelength of seismic wave with a gaussian source

I want to know how to get the wavelength/frequency of a seismic wave, if I only have a Gaussian source and the velocity (c = 4000m/s) of a medium given. e.g. for a Ricker wavelet it would be easy to ...
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2 votes
1 answer
36 views

Seismic amplitude distribution

Recorded (or raw) and processed pre/post-stack seismic data (relative amplitudes) usually display a standard normal distribution, albeit with a very small amount of skewness. What would be possible ...
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1 answer
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Seismic wavefield theory: velocity anisotropy

Does the reciprocity principle hold true in an anisotropic subsurface environment?
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1 answer
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What is the vertical axis of this waveform shown in this tweeted IRIS GIF?

This IRIS tweet shows a video of siesmic waves from the recent M6.4 Earthquake in California rolling across the US. I've made a small GIF to give the idea but the "GIF" in the tweet shows the whole ...
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1 vote
1 answer
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How to read Seismic Survey?

Recently I am tasked to create a POC on detection of patterns using a neural . But I am from a computer science background so I know about neural networks but I don't have any knowledge about geology ...
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1 vote
1 answer
154 views

wave speed is smaller than both horizontal wave speed and vertical wave speed?

I am new to GIS and just get the idea of slowness. I can understand why people need the slowness in GIS rather than just the reciprocal of velocity. However, I feel the definition of slowness is weird ...
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1 vote
1 answer
129 views

reverse time migration for wave equation PDE using SBP-SAT

I'm stuck implementing a reverse time migration technique, the PDE(partial differential equation) being implemented is an acoustic wave equation, The numerical method being used is a FD(finite ...
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3 votes
2 answers
794 views

Travel Times for Seismic Wave Types - Why reflected t-x plot curves

I do not understand how the reflected wave in a seismic survey has a steepening slope (slows down) Please bear with me as I lay out my thoughts because I feel like I can grasp all of this except this ...
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1 answer
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Near-Surface Investigations: FWI vs. MASW

MASW is a common processing method for civil/geotechnical and even for oil/gas exploration (usually weathering static corrections) applications. In my experience, it seems to work well for most ...
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4 votes
0 answers
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Seismic data acquisition: reliability of high-bandwidth data

In my research, finding and understanding info relating to the lower end of (conventional) surface seismic data acquisition (i.e. 15 - 1 Hz) is relatively simple. However, when I look at specs for a ...
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1 vote
1 answer
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Love-Wave Propagation

Love-waves cannot exist in a half-space. Layering must be present and there also must be accompanied impedance contrasts associated with the layering. Because layering naturally induces seismic ...
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3 votes
0 answers
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Difference between landslide waves and earth quake waves

I am new to this field, recently started working on landslide monitoring mainly in signal processing part. I have the following questions? 1.Will each land slide and every vibration have p wave, s ...
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1 vote
1 answer
400 views

Quality control in Seismic Acquisition - How much data is required?

When it comes to land or marine acquisition (oil exploration, for instance), I can see from literature that quality control (QC) is performed during the survey to ensure that the seismic traces ...
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2 votes
2 answers
2k views

converting segd data to SU format using seismic unix

I tried to convert segd format to su format using seismic unix by below command: segdread tape=1.segd > 1.su but I have an error: ...
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2 votes
1 answer
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Basic petrophysics

The following question was inspired by Effective pressure or what is the effect of presssure?, which may be accessed here: https://inside.mines.edu/UserFiles/File/CRA/2005/...
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2 votes
1 answer
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DC component in Hilbert transform concept for seismic data

In The Leading Edge tutorial article Phase and the Hilbert transform (Purves 2014), there is the following line: So we apply a Hilbert transform by multiplying all negative frequencies by i and all ...
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5 votes
0 answers
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How do I generate a Moho depth model from seismic refraction data?

There are several permanent seismograph stations in Eastern Canada that have been recording arrival times for over 25 years. Using refracted Pn arrival times from natural earthquakes I would like to ...
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1 vote
1 answer
102 views

Spectral Whitening, Seismic Interferometry

What is the role of spectral whitening in the processing step done before cross-correlations in seismic interferometry?
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Seismology - PPV / VDV from geophone waveform data

I'm using an inexpensive seismometer to try and measure the effects of local HGV traffic on buildings. The device is connected to a Raspberry PI that has a Cirrus Logic Audio Card. The signal is fed ...
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1 vote
2 answers
2k views

Seismic dispersion: What does it really mean and what causes it?

Body waves (to some extent) and especially surface waves show dispersive characteristics during propagation. In Dr. Christopher Liner's book [Elements of Seismic Dispersion (2012)], this phenomenon is ...
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1 vote
1 answer
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What does 'reghosted' mean in a seismic cube label?

I came across to a seismic volume labeled as reghosted. In my understanding, a seismic survey is deghosted as part of a processing step. Then I wonder why one would like to reghosted the data? Is ...
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3 votes
0 answers
43 views

Which wavelet for acoustic inversion?

If I have seismic data obtained with an explosive source (i.e. minimum phase wavelet), should I re-process the data into zero-phase data to perform an acoustic impedance inversion?
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3 votes
1 answer
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Open source well information viewer

I am in the middle of a hobbyist experiment and would like suggestions on an open source HTML viewer for mud loggging, FMIs, lithology and seismic. I have used INT before but for this project I would ...
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1 vote
0 answers
53 views

Interpretation of horizon display

I am currently working on a project that involves using seismic attributes as input parameters in a neural network for estimation of porosity and permeability for a reservoir. Now, I need to correlate ...
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0 votes
1 answer
116 views

DC component: Seismic inversion

Multiple papers (for example, Limitations on impedance inversion of band-limited reflection data Gosh[2000]) and textbooks covering seismic inversion mention a necessary component of any seismic ...
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2 votes
1 answer
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Seismic inversion: High-Frequency approximation

In numerous textbooks and papers, the phrase "high-frequency" approximation is used in regards to different types of seismic inversion. What exactly is meant by this? Also, what are the implications ...
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6 votes
1 answer
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Seismic migration concepts

In Dr Hua-Wei Zhou's book Practical Seismic Data Analysis (2014), he includes and explains figures from previous classic works (i.e. Schneider, 1971) in order to describe migration from a fundamental ...
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